RFC 793State machine study

Simultaneous close sequencePage 39, Figure 14

Simultaneous close sequence

TCP A TCP B

Page:39Figure. 14

Should_ACK=300

1. ESTABLISHED ESTABLISHED

SEQ=100 SEQ=300 Should_ACK=100

Simultaneous close sequence

TCP A TCP B

Page:39Figure. 14

Should_ACK=300

2. (Close) (Close) FIN-WAIT-1 --> <SEQ=100><ACK=300><CTL=FIN,ACK> ... FIN-WAIT-1 <-- <SEQ=300><ACK=100><CTL=FIN,ACK> <-- 0 ... <SEQ=100><ACK=300><CTL=FIN,ACK> --> 0

SEQ=100 SEQ=300 Should_ACK=100

SEQ=100 CTL=FINACK=300 DATA=

SEQ=301 Should_ACK=101

SEQ=300 CTL=FIN ACK=100 DATA=

Should_ACK=301SEQ=101

Simultaneous close sequence

TCP A TCP B

Page:39Figure. 14

Should_ACK=301

3. CLOSING --> <SEQ=101><ACK=301><CTL=ACK> ... CLOSING <-- <SEQ=301><ACK=101><CTL=ACK> <-- 0 ... <SEQ=101><ACK=301><CTL=ACK> --> 0

SEQ=101 SEQ=301 Should_ACK=101

SEQ=101 CTL=ACK=301 DATA=

SEQ=301 Should_ACK=101

SEQ=301 CTL= ACK=101 DATA=

Should_ACK=301SEQ=101

Simultaneous close sequence

TCP A TCP B

Page:39Figure. 14

Should_ACK=301

4. TIME-WAIT TIME-WAIT (2 MSL) (2 MSL) CLOSED CLOSED

SEQ=101 SEQ=301 Should_ACK=101SEQ=NA Should_ACK=NA SEQ=NA Should_ACK=NA